300 Dr. Brinkley on the 
account, except from error of observation : therefore we 
may conclude that had Dr. Bradley used the fractional parts 
of the seconds, the maximum would have been very accurate. 
We cannot now estimate the effect of this omission ; we can 
only see that it is probable it has had a sensible effect on his 
conclusion ; and we may suppose this to have been corrected 
by his subsequent revision. His words in the paper* on 
nutation are, “ I have again examined my observations that 
were most proper to determine the transverse axis of the 
ellipse, which each star seems to describe, and have found it 
to be nearest to 40"; which number I therefore make use of 
in the following computations/’ He had at first concluded it 
to be 20"^. On the whole then, it seems that 20" is the 
result deduced from the direct light of the fixed stars, and 
2Q #/ i from the solar light reflected from Jupiter’s satellites. 
It is highly probable that future observation will find these 
quantities exactly equal. At present there exists an uncer- 
tainty. 
Note (B. ) 
The results of the attempts of Hooke and Flamstead are 
remarkable ; the former reasoned justly on inaccurate ob- 
servations, and the latter wrong on exact ones ; and both 
imagined they had discovered a parallax. Hooke, who 
erected at Chelsea a fixed telescope, 36 feet long, for observ- 
ing 7 Draconis, found a change of place agreeing with a 
considerable parallax. The great mechanical skill of Dr. 
Hooke, the length of his telescope, and the precautions he 
took, seemed to leave no doubt. 
Dr. Bradley, in his paper on the aberration, expresses great 
* Phil. Trans, xlv, i ; or Old Abridg. x, 32. 
